Tavannes Clamshell Case Vintage Chronograph Venus 175

A rare vintage chronograph
in a patented, waterproof
"Clamshell" case
Brevet 189190
Tavannes
caliber Venus 175

This chronograph has a patented watertight case, so-called Clamshell case. The case part is fixed in the calotte with 4 worm screws / grub screws in the lugs. The Clamshell case, patented in 1937 by Schmitz Freres with patent no. 189190, consisted of a watertight compartment that held the movement secured to the case body by four screws.
Details on the watch
Dial
black
Arabic numerals
inner five-minute divisions
45 min. counter
auxiliary seconds
telemeter- and tachymeter scales
gilt hands
very good condition

Movement
rhodium plated
caliber Venus 175
17 Jewels
finely ground chronograph steel parts
ratchet wheel
gold wheel train
fine adjusting device
ruby endstone on balance
screw balance
signed "Tavannes"
The movement was professionally overhauled, it is fully functional and running very well.

Case
steel case
two body
screw back
diameter 36mm without crown
lenght 42.5mm
signed
very good condition

Bracelet
new leather bracelet
The watch is fully functional, is running very well and is in a very good total condition.